1. Field of the Invention
The present invention relates to a device for guiding a cloth-like member or cover member to a sewing machine adapted to sew a trim cover assembly for automotive seat. More particularly, the invention is directed to a device for guiding to such sewing machine a three-layer-lamination-type trim cover assembly having a curved or wavy edge.
2. Description of Prior Art
In a commonly practiced process for producing a trim cover assembly for automotive seat, several separate pieces of base cover members are sewn together at and along their respective mating ends by use of a sewing machine in order to form a trim cover assembly. Generally, for instance, the first step involves providing two separate base cover members, one of which forms a central seating cover section corresponding to a central seating area of the seat, and another of which forms a peripheral side cover section corresponding to the lateral side wall of the seat surrounding the central seating area of the same. Then, in the second step, both ends of those two base cover members are sewn together by a sewing machine to create a trim cover assembly which is to be affixed over a padding member having an outer shape of automotive seat.
The foregoing sewing processes, in some cases, utilize two separate pieces of three-layer-lamination-type base cover members, each or one of which has a curved or wavy end and comprising the following three layers: a top cover member, a wadding (made of a slab urethane foam material) and a wadding cover (a non-woven cloth) which are laminated in this order. In that particular case, it has been difficult to sew such two base cover members together along their respective ends. That is, conducting a manual sewing thereto requires a high skill on the operator's part, which frequently results in producing undesired different sizes or shapes of trim cover assembly, depending on the technical artisan ability of individual operators, or alternatively, an automated sewing arrangement may be contemplated thereon, but any technical solution in the automated sewing mechanism has not been found to precisely and easily sew together those two three-layer cover members along their curved or wavy ends.
Of course, with regard to the automated sewing arrangement, there has been known several automated sewing machines and systems, such as the ones disclosed from the U.S. Pat. Nos. 4,899,674, 4,899,675 and 4,928,609, and the Japanese Patent Laid-Open Pub. No. 58-188492. All of them are based on such construction that a base plate is provided on a table of sewing machine, the base plate having two or more guide grooves formed therein, a plurality of rollers are slidably inserted in the guide grooves and a guide means (e.g. a small movable plate, a movable arm or a stationary guide member) is fixed to the rollers, whereby the curved end of one cover member is sewn to the likewise shaped or rectilinear end of another cover member, with the guiding aid of such guide means being moved along the guide grooves via the rollers, which guide grooves define a given track that ought to be followed by the guide means per se in order to cause a curved or rectilinear end of one cover member to be sewn to and along a curved, wavy end of another cover member.
However, in practical case, when the above-stated three-layer base cover member is applied to such prior-art automated sewing machines, a substantive amount of feeding force is required in the sewing machine itself to feed that thick element, which in turn encounters an non-smooth sliding movement of the guide rollers along the guide grooves. As a result of this, an ordinary sewing machine can not work in this particular case, or rather, this is especially true when sewing a rectilinear end of one cover member along an acutely curved or very irregularly wavy end of another cover member, because it requires preparing many different base plates with various shapes of guide grooves, or it will inevitably bring about a mutual interference of the guide rollers in the guide grooves due to the acutely curved end of cover member. Moreover, this makes it difficult to sew a linearly extending bead together with and along that curved end of cover element for decorative purpose. Also, in terms of setting a precise sewing position for both cover members, the prior arts have been with such further problem that even a slight dislocation of the cover members with respect to the base plate, or a slight difference in size between the two cover members, will differ a sewing point from a fixed sewing position of the sewing machine, hence making it impossible to maintain a constant fixed sewing position in the actual sewing process which may often involve such slight dislocation or slight size difference problem.